This invention relates to the field of simulation systems, and in particular to a network simulator that includes models of wireless nodes or other forms of broadcast communications.
A network simulator is an analysis tool that provides information that is useful for network planning and evaluation. New or existing networks can be analyzed to determine network performance, identify communication bottlenecks, estimate throughput capacity, and so on. Proposed changes to networks can be evaluated via simulation before they are implemented, so that informed choices can be made among considered alternatives.
The simulation of a complex network consumes a substantial amount of computer resources. In a conventional network simulation, the transmission of a packet of information is simulated by the propagation of “events” from one node/element in the network to another. The generation of the packet at the source node is an event that is propagated to the first node along the communication path of this simulated packet. The arrival of this packet at the first node is an event that triggers the modeling of the propagation of this event through the first node, resulting in the generation of a subsequent transmission event from this node and a reception event at the next node along the communication path. This reception event triggers the modeling of the propagation of the event through the second node, and the subsequent transmission-reception events to the next node, and so on. To simulate actual network performance, the processing of an event at a node may trigger multiple events, such as a simulated error likelihood at each node that may result in requests for retransmission from sending nodes.
The scheduling of each of these events and the modeling of the processing of each event through each node consumes computer time and memory, and if there are many simulated transmissions of packets and/or many nodes in each communication path, the simulation of a complex network can take hours, or days, to complete.
The simulation of a “broadcast” event, such as the transmission of a packet from a wireless device, or the transmission of a packet along a cable-TV network, further exacerbates the scheduling and modeling resource requirements of a network simulator. In a conventional point-to-point wired network, a transmission event from one node results in a single reception event at another node. In a wireless network, a transmission event from one node often results in the generation of a reception event at each of the nodes that are within range of transmitting node. In like manner, a transmission event from a cable-TV provider results in the generation of reception events at each receiving node.
An objective of this invention is to provide an efficient method of simulating broadcast traffic in a network simulator. A further objective of this invention is to substantially reduce the processing time associated with the simulation of broadcast traffic in a network simulator. A further object of this invention is to substantially reduce the number of simulated interactions associated with broadcast traffic in a network simulator.
These objectives, and others, are achieved by providing a simulation method and system that partitions network traffic into background traffic and explicit traffic, wherein explicit traffic is processed in detail, and background traffic is processed at a more abstract level. The packets of explicit traffic are modeled in complete detail, so that precise timing and behavior characteristics can be determined, whereas large volumes of traffic are modeled more abstractly as background flows, and only certain aspects, such as routing through the network, are simulated. Tracer packets are used to model the background traffic and carry a number of characteristics of interest for generating simulation results. These tracer packets are propagated through the network in the same manner as any other simulated packet and therefore are processed through each element traversed by the propagation of the background traffic, but each single tracer packet is representative of all of the packets comprising the modeled background traffic. In this manner, the effect of the background traffic on the explicit traffic can be modeled at each network element. The abstract processing of background traffic is facilitated by techniques that include multi-variate table look-up, neural networks, and the like.
Throughout the drawings, the same reference numerals indicate similar or corresponding features or functions. The drawings are included for illustrative purposes and are not intended to limit the scope of the invention.